My savings are even better - partly because gas costs more in Canada and partly because I have a 10KW solar system on my garage roof. I really notice the difference in my monthly credit card statement!
My previous BMW 6 Gran Coupe used about 10 litres per 100 kms. At 18,000 kms per annum, that's 1800 litres at roughly CDN$1.30 per litre for premium gas. So my annual gas bill was in the range of CDN$2340.
My electricity charges outside my home have been April $15, May $0, June $0 July $25, August $0. This is an average of $8 per month. Say $100 per annum - an estimated saving of $2240 a year. (I should say that I have used free charging at hotels several times and I have not included any costs for that.)
As you can see, nearly all my charging is at home. I have driven the car about 7,000 kms in 5 months.
The other side of the coin is, of course, the cost of the solar system, but - I also use it to heat my home in the winter.
If I were to ascribe a cost to the electricity I use at home, using Ontario Hydro rates, my total cost would have been April $38, May $55, June $81, July $59 and Aug $24. This is an average of $52 per month, or $624 a year. Still a saving of at least $1,700 a year.
Then add the savings of oil changes etc and the finances are pretty attractive - assuming you're going to own a premium vehicle in the first place. Ironically though, it's my desire to be green that is more important to me than the money.